For many young Star Wars fans, the most iconic moments from the original movie trilogy were the dogfights between the Rebel Alliance's X-Wings and the Galactic Empire's TIE Fighters. As the massive sales of the later X-Wing computer games show, the fighters have remained hugely popular.
In a video today, director J.J. Abrams revealed the design of a new generation of X-Wing fighter. Coming from a generation (or two) further on from the originals, these X-Wings are sleeker and appear to split their wings on a vertical axis rather than horizontal (with the wings appearing to pop up from behind one another, a bit like some of the prequel trilogy proto-X-Wings). There's also no sign of a housing for an astromech droid, suggesting they are no longer needed or are stored internally, which, as R2-D2 can attest from the end of Episode IV, makes a hell of a lot more sense.
These new X-Wings appear to also be a homage to Ralph McQuarrie's amazing concept art for the original films. One of McQuarrie's ideas was that the X-Wings would have two large engines which would split, rather than four smaller ones that would not.
There's also something of a design similarity to the Z-95 Headhunter, a predecessor design to the X-Wing developed for the Expanded Universe which enjoyed great fan popularity before appearing in The Clone Wars (and thus becoming canon even for the new Star Wars continuity).